2) Check your screen resolution and also the screen refresh rate. You can find the screen refresh rate in display properties --> "Settings"tab --> Click on the "Advanced" button --> Click on "Monitor" tab --> Now try another "Screen refresh rate". [Note : Make sure that "Hide modes that this monitor cannot display" is selected]
3) If the problem still exists then When you switch ON your laptop, keep pressing the "F8" key to get "Windows Advanced Options"( if boot menu appears, press "Esc" key and keep tapping the F8 key). Select the option "Enable VGA Mode" --> Press Enter
4) If the problem still exists then Connect an external monitor to your laptop. Just look for the VGA connector ( there will be a monitor symbol ) in your laptop and connect it to the external monitor then switch ON your laptop.
Note : If you failed to get the display in external monitor, then use the proper combination keys(like Fn+F5/ the function key that's having the monitor symbol on it) to toggle between your laptop screen and the external monitor.
Now check if the flickering problems exists in the external monitor or not.
If the flickering problem only exists on the laptop screen then the problem may be coming from the inverter which is going bad.